diff --git a/src/fastcontext/agent/tool/grep.py b/src/fastcontext/agent/tool/grep.py
index 4ee161f..9f2e96c 100644
--- a/src/fastcontext/agent/tool/grep.py
+++ b/src/fastcontext/agent/tool/grep.py
@@ -75,7 +75,7 @@ async def call(self, parameters: str, **kwargs) -> str:
         output_mode = params.get("output_mode")
         before_context = params.get("-B")
         after_context = params.get("-A")
-        context = params.get("-C", 3)
+        context = params.get("-C")
         line_number = params.get("-n", True)
         ignore_case = params.get("-i", False)
         type = params.get("type")
diff --git a/tests/test_grep_context.py b/tests/test_grep_context.py
new file mode 100644
index 0000000..06a1dda
--- /dev/null
+++ b/tests/test_grep_context.py
@@ -0,0 +1,28 @@
+import asyncio
+import json
+import tempfile
+from pathlib import Path
+
+from fastcontext.agent.tool.grep import GrepTool
+
+
+def _search(grep, cwd, params):
+    return asyncio.run(grep.call(json.dumps(params), cwd=cwd))
+
+
+def test_grep_no_context_unless_requested():
+    """content mode must not inject surrounding context by default; -C only
+    applies when the model explicitly provides it."""
+    grep = GrepTool()
+    with tempfile.TemporaryDirectory() as cwd:
+        (Path(cwd) / "a.txt").write_text("before\nMATCH here\nafter\n", encoding="utf-8")
+
+        # No -C: only the matching line, no neighbors.
+        out = _search(grep, cwd, {"pattern": "MATCH", "output_mode": "content"})
+        assert "MATCH here" in out
+        assert "before" not in out, f"unexpected default context: {out!r}"
+        assert "after" not in out, f"unexpected default context: {out!r}"
+
+        # Explicit -C: neighbors are included.
+        out = _search(grep, cwd, {"pattern": "MATCH", "output_mode": "content", "-C": 1})
+        assert "before" in out and "after" in out, f"expected context with -C=1: {out!r}"